MANILA China warned the Philippines on Tuesday that its arbitration case before the United Nations over a maritime dispute "seriously damaged bilateral relations" and called on Manila to return to negotiations.
The Philippines submitted the case, challenging China's "nine-dash-line" that stretches deep into the South China Sea and the maritime heart of Southeast Asia, on Sunday.
"We find it very hard to understand these moves of the Philippines and we are deeply disturbed by and concerned with the consequences of such moves," said Sun Xiangyang, charge d'Affaires of the Chinese embassy in Manila.
"What the Philippine side did seriously damaged bilateral relations with China."
Sun said China would not participate in the legal process because it did not believe the court case would resolve the dispute.
"We hope that the Philippine side will correct its mistake and come back to the right track of resolving the disputes through bilateral negotiations," he said, adding China had not shut the door to negotiations.
In Beijing, the ruling Communist Party's official People's Daily said in a long commentary that the Philippines was trying to win international sympathy by portraying the dispute as a struggle between a small country and a big one.
"China is not in the wrong, and is not scared," it wrote.
Beijing's claim over islands, reefs and atolls that form the Spratlys, a group of 250 uninhabitable islets spread over 165,000 square miles, has set it directly against U.S. allies Vietnam and the Philippines, while Brunei, Malaysia and Taiwan also lay claim to parts of the South China Sea.
Last week, a small Philippine government ship evaded a blockade of Chinese coastguard vessels to deliver food, water and fresh troops to a navy transport that ran aground in a disputed shoal in the Spratlys.
The cat-and-mouse encounter on Saturday offered a rare glimpse into the tensions playing out routinely in waters that are one of the region's biggest flashpoints. It's also a reminder of how assertive China has become in pressing its claims to disputed territory far from its mainland.
On Monday, the U.S. State Department accused China's coastguard of "harassment" of Philippine vessels.
Chinese Foreign Ministry spokesman Hong Lei said it was the Philippines which was the troublemaker, urging Washington to "respect the facts" and "stop assisting the relevant countries' risky and provocative behavior".
Philippine armed forces chief of staff General Emmanuel Bautista told reporters the Philippines was not being provocative.
"We are just doing our jobs to resupply our troops," he said. "...We will be ready with any consequences. The fact that we pursued with our case means we're prepared."
Sun said the Philippines has failed to notify China about its arbitration case and that Manila also disregarded China's position that it does not accept the process.
The court will now ask China to respond to the Philippines' position, but Beijing can choose to ignore it. Manila does not expect the tribunal to reach a decision before the end of 2015.